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This species is distinguished by a lateral line that is incomplete (2-33; mode 15) and oral barbels that are inconspicuous (Ref. 124213).
Description: Body fusiform, moderately laterally compressed; dorsal profile convex, with straight ventral profile from tip of the snout to origin of pelvic fins; greatest body depth at the anterior base of dorsal fin; post-dorsal profile gently tapers to the base of caudal fin; head relatively small, its length subequal to body depth; snout short, bluntly rounded, equal to or slightly longer than eye diameter; mouth small, terminal, with a single pair of posterior barbels; barbels not surpassing the middle portion of the eye; eyes relatively large, round, and situated dorsolaterally, nearer to tip of snout than distal margin of operculum; scales moderately large, radiately striated; scale rows along the lateral line to end of hypural plate 2-5 (mode 12); lateral line incomplete, or pored lateral line scales variously interrupted (only 2 of 52 specimens with complete lateral line); circumpendicular scales 12-16 (mode 16); pre-dorsal scale rows 13-14 (mode 13); scale rows between origin of the dorsal fin and lateral line 3-4 (mode 4); scale rows between origin of pelvic fin and lateral line 3-4 (mode 4); scale rows between lateral line and anal fin origin 3-4 (mode 4)’ scales between posterior edge of head and dorsal fin embedded and smaller than flank scales; dorsal fin almost in the centre of the body, with three unbranched and seven branched rays; pectoral fins fan-shaped, posterior edges are gently rounded, not reaching pelvic fin origin; pelvic fin with eight rays, origin slightly in front of dorsal fin origin, tip of adpressed pelvic fin does not reach anal fin origin; anal fin with three simple rays and five branched rays, its distal margin almost straight and the origin closer to pelvic fin origin than to caudal fin base; caudal fin forked, its lobes gently rounded with moderately pointed tips. Colouration: alive and fresh specimens are pale silver with a small dot at mid base of caudal fin (Ref. 124213).
This species differs from its congeners cernuus, mandelai in having an incomplete lateral line, pored scales 2-33, mode 12 (vs. 15-37, mode 35); differs from amatolicus, motebensis, gurneyi by absence of tubercles on the head during breeding season (vs. development of nuptial tubercles on either snout, lower jaw, forehead or sides of head in the other species); further differs gurneyi, motebensis by having a single pair of barbels (vs. two pairs of barbels); differs from amatolicus by having short barbels that do not surpass vertical through middle of eye (vs. distinctly long barbels that surpass vertical through posterior edge of the eye); differs from unitaeniatus, viviparus, lineomaculatus, barotseensis by the lack of distinct lateral line chevron markings and with a single pair of relatively short maxillary barbels not
exceeding middle portion of eye (vs. presence on the lateral line of conspicuous chevron markings and the existence of two pairs of long and prominent barbels exceeding middle portion of the eye); differs treurensis, breviceps, annectens, pallidus, brevipinnis, radiatus, bifrenatus by having one pair of oral barbels (vs. two pairs of long barbels); differs from neefi, pallidus by the absence of two pairs of oral barbels and the absence of dispersed black spots on the body (vs. with two pairs of oral barbels and black spots on the body); differs from fasciolatus by the absence of prominent vertical bars along the body (vs. present) (Ref. 124213). |
| Reports on extensive studies of the biology and ecology of this species, were mainly focused on populations from Lake Le Roux in the Orange River system. The species occurs in a number of habitats ranging from tributaries to mainstem sections of rivers and man-made impoundments where it is usually associated with vegetated areas. Observed early maturation in the first year of life, high reproductive effort, having multiple clutches per year and rapid growth rate are important traits that makes this species highly adaptable to habitats that are prone to regular input of high silt loads and experience extreme variation in flow regimes, ranging from devastating floods to erratic flows. Reported spawning events occur following the onset of rainfall in summer, where fish spawn locally, although spawning migration has been occasionally observed, with adhesive eggs laid in flooded marginal vegetation, This species has early maturity (attains 4.0 cm FL in first year), high reproductive rate (a female of 6.3 cm can have up to 3250 eggs) and a protracted reproductive season (up to 6 months) with individuals able to have multiple clutches. These traits allow survival in the dryland southern tributaries of the Orange River system that drain the Great Karoo (Ref. 124213). |
